You did try, but what exactly? Do you know, what differences between input and output signals are most important, what should we look via a microscope, and what can be looked at from 10m distance, what kind of input signal should be used?
Just these questions are the subject of many thousands of post. Saying that every distortion must be nulled, this fits a level of a beginner, who did not play with high level systems and designs.
100dB under useful signal, in a perfect, for instance, tube-based system, is very audible, even -140dB. Hundreds of people discuss the resistors effects. Prof. Malcolm Hawksford, well known to many, selects passive parts at listening sessions, that means he also listens -140dB. Tube lovers distinguish every individual resistor easy, and measurable resistor distortions correspond to -140dB level.
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Um... How does one hear the input signal?
se
Ahh! Finally someone who thinks
That's the crucial question in any case. I would bet on digital comparison.
Analog comparison probably doesn't get you any better nulling than 100dB and it has been stated that trained listeners can hear differences that small. Although what I've read in studies is that that sensitivity has been seen with artificial signals, not with music.
Bill Waslo's Diffmaker shows that most listeners cannot detect a sousa band 60dB down to the main classical music.
Digital comparison probably gets you down to 22 or more practical bits resolution, say better than 130dB nulling. I don't think you can make a realistic case that music signals that are identical down to -130dB can sound different.
From that level you could progressively make the sound more different and see when a difference can be detected reliably and repeatably. That established your hearing treshold. It will most probably differ with music and of course between persons, so you should add a 'safety factor' of maybe another 10-20dB.
Would that make sense?
jan didden
Yes I know that schematic, from the WW article where you cut if from. Peter Walker I think.
IIRC it didn't really get any better than 60dB nulling or so. The problem is the phase shift between input and output that varies with frequency and may even vary dynamically unless you have a really good amplifier.
jan didden
I think you mix up a lot of different things. I am not aware of any documented, controlled test that shows audibility of non-linearities down to -140dB. Almost everybody I know fails the mentioned Diffmaker test at -60dB, and that is a controlled test.
And it doesn't matter what distortion there is. If the sound sounds the same to a listener, it is the same (for the listener). No need to look at somethings under a microscope and at somethings at 10m (32.808 feet). You seem to be hung up a lot on THD, you mention it all the time, but it is *just* a method to measure a certain non-linearity.
Nobody distinguishes 'every individual resistor easily' except in casual, anecdotal 'friends' tests. If you want to be serious, you need better arguments. Even 100.000 posts here mean nothing because most just copy what they hear from others.
jan didden
Ahh! Finally someone who thinks
That's the crucial question in any case. I would bet on digital comparison.
I'll leave that to others. I'll just stick to listening to the output signal.
se
The world is going to separatism.
At serious tube forums, nobody would discuss your explainations, they simply would suggest to change the forum, to so-called engineer's forum.
And, vice-versa, people that hear effects of resistors and capacitors are not welcomed at the engineer's forums.
The languages are different, and this will remain, probably for a long time. Sometimes engineers drift to the audiophile camp, when they happened to live with a top-level system, but a reverse drift never happens.
I am lost completely from many of engineers arguments, like someboby does not distinguish -60dB, or -100dB. Everything depends on the system, including cabling, power etc. System is a measurement instrument in such a test, and who bothers to specify this instrument, in the hearing-related metrics?
Where you see active components? The only is tested amplifier.Amps behind summing point (conection R, 20R) only amplify residual errors to audible levels for analyse
You are really lost, You believe , you can hear in loud sound artefacts 100dB below this sound??And posted test is exclusively hearing related, no measurement instruments.
2 jan
I get more than 90dB supresion in 20Hz-20kHz range.
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Sure, some people are happy with what they do & have and listen to, what's wrong with that? If you are not interested in any explanations, that's your good right. I can't see what problem anyone would have with that? You don't have to participate in any thread if you don't want to.
jan didden
Yes, VladimirK, you are correct. It saddens me, because it makes it so difficult to openly discuss what we find important, except privately by personal correspondence by phone or e-mail. My colleagues and I go on for hours, discussing our latest 'discoveries' and give each other suggestions.
Just yesterday, I spoke at length to Dick Sequerra about amplifier design. He gave me more advice than I really knew what to do with at the moment, but again he reiterated about FM distortion in solid state, EM fields within the equipment, and lots of other things. He also asked me to say hello to Scott Wurcer, and tell him that he should cut out the HS, because it would seem impossible for Scott to not understand and appreciate these subtle problems that we attempt to discuss here.
Personally I don't mind controversy, but virtually everybody I know is attacked, including Vandenhul, Bybee, Hawksford, and all the audio reviewers, who usually have access to better test equipment than their critics, and certainly more experience.
It would be nice to be able to discuss our 'findings' amongst ourselves without being teased and 'hooted down'.
Just yesterday, I spoke at length to Dick Sequerra about amplifier design. He gave me more advice than I really knew what to do with at the moment, but again he reiterated about FM distortion in solid state, EM fields within the equipment, and lots of other things. He also asked me to say hello to Scott Wurcer, and tell him that he should cut out the HS, because it would seem impossible for Scott to not understand and appreciate these subtle problems that we attempt to discuss here.
Personally I don't mind controversy, but virtually everybody I know is attacked, including Vandenhul, Bybee, Hawksford, and all the audio reviewers, who usually have access to better test equipment than their critics, and certainly more experience.
It would be nice to be able to discuss our 'findings' amongst ourselves without being teased and 'hooted down'.
You are not "amongst yourselves". You are on a public forum. Amongst yourselves would be be private emails or similar.
I missed that one, link? He did show some spectra of amps where one had fairly obvious mains IMD on the test tones (poor supply). He never answered my question.
I would think taken on face value there would be several test files floating around for anyone to try. IIRC many of his "transfer functions" would not likely be created with normal audio systems.
EDIT possibly you mean his first (?) thread, where he mentioned his $150 Pioneer receiver and stated flatly speakers are 99% of the problem. My impression was he meant crossover distortion that gives .01% at full power but >> at -60dB. Hardly a new observation.
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